Method for financing multimedia content through advertising

ABSTRACT

Advertisers who finance the showing of useful data have an interest in ensuring that mixed-in sequences of advertisements are really shown and not skipped by means of intermediate recording. In order to make the showing of the useful data dependent on the reproduction of the sequences of advertisements, code elements of a key are embedded at certain points in the sequences of advertisements. While the sequences of advertisements are being played back, these code elements are scanned and collected, then combined to produce a complete key. If the subsequent useful data are encrypted with this key, their reproduction is dependent on the key. This method of making the reproduction of the useful data dependent on the reproduction of the sequences of advertisements can be used for known advertising-financed free TV, known and initialized recording methods and new advertising-financed multimedia content and products.

[0001] The present invention relates to a method of the type defined in detail in the preamble of Patent claim 1. Such methods are known in general from advertising-financed free TV, where they are widespread and are used by advertisers who wish to finance the presentation of useful data by presenting mixed-in sequences of advertising blocks.

[0002] The distribution of media is often financed by advertising breaks. This is not a problem today in the area of television, because the customer cannot “fast forward” a television broadcast. The custom of “zapping” is taken into account by broadcasters by extensive synchronization of advertising.

[0003] The situation is different in the area of recorded content, e.g., when television broadcasts are recorded on videocassettes, where the user often has the option of bypassing the advertising by fast forwarding the videotape until the advertising is terminated. This problem occurs mainly in the video area but is also conceivable for other media (CDs, DVDs).

[0004] This problem receives a new dimension with a development which is bundled by the “TV Anytime” standardization initiative (http://www.tv-anytime.org/): In the future, television sets, video recorders and/or set-top boxes will contain memory media (e.g., hard drives with a capacity of 50 to 100 Gigabytes) which will make it possible to record and play back the content simultaneously as desired. This will make it much easier for the customer to skip the advertising breaks:

[0005] The customer will record about 15 minutes of the broadcast.

[0006] Then he will begin to watch it.

[0007] Whenever an advertising break occurs, he will skip the break and will start again after the break.

[0008] Protection of content was an important concern of the DVD standardization forum (www.dvdforum.com). Therefore, an encryption system (content scrambling system, CSS) has been specified for DVD. According to this system, a header preceding each data block on the DVD contains the title key encrypted with the disk key. Using this title key and a few extra bits, it is then possible to decrypt the content of the file.

[0009] The object of this invention is to provide a method and a device with which it will be possible to ensure that the advertising must in fact be played back. (It is of course impossible to force the customer to watch it.) This method will also make possible new types of marketing for advertising-financed content.

[0010] This object is achieved by the present invention with the method steps indicated in the characterizing part of Patent claim 1.

[0011] A device suitable for achieving this object is described in the characterizing part of Patent claim 6.

[0012] Advantageous embodiments and refinements of the method are characterized in Subclaims 2 through 5.

[0013] The invention is described in greater detail below on the basis of a few exemplary embodiments.

[0014] The method according to the invention divides content (e.g., a film) into various blocks, each being encrypted with a title key. Then unencrypted advertising blocks containing the key are inserted before and between these blocks. A playback device must scan most or even all of the advertising block to arrive at the key. A few variants are described as possible implementations below, although no claim at completeness is made here.

[0015] The simplest possibility is to conceal the entire title key in the advertising block at a randomly selected point in time. The playback device must then scan approximately half the advertising block on the average to find the key. Dividing the key into two code elements which are distributed at random points in time in the first and second halves of the advertising block forces scanning to be continued over a longer period of time, which increases in proportion to the division into more code elements.

[0016] Another possibility is to break down the title key into several partial secret codes, which are concealed in the advertising block using secret sharing schemes. These are schemes in which one must have multiple partial secret codes, which are then combined to form a complete secret code (literature: Beutelspacher, Schwenk, Wolfenstetter, Modeme Verfahren der Kryptographie [Modem Methods of Cryptography], Vieweg Verlag, 3^(rd) edition, 2000).

[0017] This principle greatly prolongs the amount of time required for scanning the advertising block by introducing a partial secret code into the data at certain intervals (e.g., in each advertising spot or every 10 seconds). These partial secret codes are then collected during playback, e.g., by the playback device.

[0018] The useful data file following is then encrypted by using the complete secret code as the title key and is then displayed only when a sufficient number of partial secret codes have been collected.

[0019] The conditions under which this is the case will depend on the secret sharing scheme used. Variations in which all or only a portion of the advertising must run are conceivable, in which case one portion may be obligatory and other portions may be optional.

[0020] Other variants of the method may be appropriate with regard to the completeness of the code elements.

[0021] The variant in which all the partial secret codes must be collected is appropriate only in the case of prerecorded media such as CDs, DVDs or videos. It is possible to ensure here that a playback device can in fact actually receive all the partial secret codes.

[0022] According to the second variant, k of n partial secret codes must be collected. This variant is recommended for radio broadcasts, because a customer may turn on the broadcast later and thus would not have an opportunity to collect the partial secret codes. If the listener turns on the program only after the advertising break, he must either wait a certain “penalty time” until he has collected enough partial secret codes outside of the advertising break or he must retrieve the session key from a server online.

[0023] The way the partial secret codes are introduced into the data depends on the medium. An implementation by using digital watermarks is also conceivable.

[0024] Another variant involves inserting the following as additional digital information:

[0025] In this case the partial secret codes are represented as specific parts of the additional program information on a digital level, e.g., as part of the service information (SI) in digital television according to DVB, as additional information in the data part of DVD (encryption by CSS algorithm) or as a separate IP packet in IP-based streaming applications.

[0026] Another variant involves insertion of a watermark.

[0027] In this case the data is contained as a watermark in the content itself. This prevents scanning of the additional digital information using auxiliary programs. The complexity required by such scanning would be equivalent to displaying the content and would not yield any advantages.

[0028] New products may be implemented with the help of the invention described here:

[0029] Terminals for receiving certain cable programs or advertising-financed broadcasts and/or playback devices for recordings containing advertising blocks,

[0030] Free giveaway DVDs, MPEG-CDs, audio CDs financed by advertising inserts (e.g., a DVD about the history of cycling interrupted by Telecom advertising blocks on Team Telecom as a present at the T points, or the new James Bond movie in which, each time a BMW appears in the movie, the corresponding advertising block for this model is blended in).

[0031] Advertising-financed content for TV Anytime. 

What is claimed is:
 1. A method of financing multimedia content through advertising, the contents including the playback of advertising blocks between uses of the content, so the advertisers finance the use of the content, wherein code elements of a key are embedded in certain locations in the advertising blocks, these code elements of a key are scanned and collected during the playback of the advertising blocks, the code elements are linked schematically to form a complete key, the following content is encrypted by using the complete key, use of the content is made to depend on a part of the code elements to be determined by the advertiser, and/or the complete key and is blocked if this part is not reached.
 2. The method as recited in claim 1, wherein the positions in the advertising blocks are selected variably, i.e., randomly.
 3. The method as recited in claim 1, wherein partial secret codes of a shared secret system are used as code elements and are combined to form a complete secret code, the extent of which is predetermined.
 4. The method as recited in claims 1 through 3, wherein the key and/or the partial secret codes are represented in the advertising blocks as special parts of the additional program information on a digital level, in particular as part of the service information in DVB digital television and/or as additional information in the data part of DVD and/or as separate IP packets in the case of IP applications.
 5. The method as recited in claims 1 through 3, wherein the complete key and/or its code elements are inserted as a watermark into the content of the advertising blocks.
 6. A device for implementing the method as recited in claims 1 through 5, wherein terminals for the preferred playback of stored or transmitted advertising blocks, in particular those issued under preferential conditions, are provided with decryption equipment which controls the collection of the code elements of the method and is connected to a blocking circuit which releases the content only if the advertising blocks are fully played back. 